Various manufacturing processes involve affixing elements to one or both ends of a rod-shaped member. One specific application for such a process is the manufacture of cotton swabs. Such products may be manufactured with cotton fibers or other types of fibers secured to one or both ends of a paper, plastic or wooden stick with adhesive. During manufacture, it is important to properly apply the adhesive to one or both ends of the stick before application of the cotton fibers. Too little adhesive will result in unsatisfactory adherence of the fibers to the stick, while excessive adhesive application will result in undesirable manufacturing downtime due to the clean up of adhesive dripping or otherwise being flung from the stick during the manufacturing process. While meeting the precise quantity requirements of adhesive application, the manufacturing process must also consistently apply the adhesive around the end or ends of each stick and must do so in a high speed manufacturing environment to hold product manufacturing costs as low as possible.
One current process for manufacturing cotton swabs involves rapidly conveying the sticks past a rotating wheel which has a lower portion thereof in contact with a container of adhesive. The adhesive therefore continually coats the circumference of the wheel. As the ends of each stick contact the upper portion of the spinning wheel, the ends are simultaneously rotated and coated with the adhesive. While this method allows for a rapid production speed, the above noted problems exist with this type of process. Specifically, the wheel can accumulate too much adhesive on its circumference and, therefore, apply too much adhesive to the ends of the stick. Some of this adhesive will fall or be flung off the ends of the stick necessitating manufacturing downtime in order to clean up the excess adhesive. Also, because the adhesive is exposed to the environment prior to its application on the stick, the adhesive can accumulate various airborne contaminates. This can reduce the effectiveness of the adhesive and lead to unsatisfactory adherence of the fibers to the stick. The use of a wheel to apply adhesive to the sticks may also lead to inconsistent adhesive deposition as a result of inconsistent amounts of adhesive on the circumference of the wheel. For example, as the level of adhesive in the adhesive supply becomes reduced, there may be less adhesive applied to the circumference of the wheel and, conversely, when the supply is increased, increased adhesive contact is made with the wheel resulting in increased amounts of adhesive on the wheel. These characteristics of this existing process correspondingly result in decreased or increased amounts of adhesive being applied to the ends of the sticks.
Another previously proposed manufacturing method for cotton swabs generally involves the use of an on/off adhesive dispensing valve having slot nozzles positioned in the respective paths of the ends of the sticks. The sticks move over the slot nozzles which are activated and the sticks simultaneously rotate such that the ends of the sticks receive the discharged adhesive. The challenge associated with this proposed method is that the rod or stick must be rotated quickly enough as it passes the slot nozzles to ensure coating of the entire circumference of each end. In order for this to occur, line speeds may have to be reduced to an undesirably low level or spinning rates of the sticks may have to be increased to an impractically high level. Even if the speeds are adjusted to ensure a full rotation directly over the slot nozzle, the slot nozzle may still not apply adhesive in an evenly distributed amount to the entire outer surface of each stick end.
For these and other reasons, it would be desirable to provide a system and method for applying adhesive to one or both ends of a rod-shaped member in a uniform, consistent manner, and in precise amounts, while maintaining the high manufacturing speeds necessary to hold down product manufacturing costs.